I propose to develop a computer model of bacterial growth, based on our current understanding of the control of synthesis of ribosomes, RNA polymerase, chromosome replication and cell division that are being studied in my laboratory. I propose to study the implications of this model and to continually refine it as new experimental data become available. The model would simulate physiological experiments like nutritional shifts, changes in replication velocity or inhibition of macromolecule synthesis rates by specific drugs, or the behavior of mutants with a defect, e.g. the control of DNA replication or ribosome synthesis. Such mutants have been isolated and are being studied in our laboratory. The model is expected to improve our understanding of bacterial physiology and to serve as an aid for data evaluation and guide for experimentation.